FOR serious, this-worldly folk, the millennium probably means little more than wondering how to spend (or avoid) new year's eve and hoping that the company payroll does not get lost in the electronic ether. For the people Alex Heard has been talking to across the United States for roughly the past decade, the dawn of the 21st century involves waiting for enlightened space travellers, stockpiling food and ammunition for an environmental Armageddon or preserving severed human heads for the day when all disease can be cured. And that is a mere taster of Mr Heard's fascinating, at times frankly loopy, cornucopia.

Mr Heard, an editor of Wired, a glossy monthly devoted to the digital age, looked for his subjects among fringe groups that evangelise on the Internet or pamphleteer at New Age conventions. Wanting to hear from people “anticipating or somehow working toward a heroically different world”, he met members of Earth Changes, a group convinced that Mother Nature seeks revenge for mankind's destructive tendencies and is “willing” on the planet a new era of natural disasters and disease. In rural Mississippi, he found Pentecostal Christians who are breeding red heifers for sacrifice in Israel, when (perhaps next year) the second coming reclaims Jerusalem's Temple Mount from Muslims. He describes Arthur Blessitt, who aims to carry an 80lb replica of the Christian cross to every country in the world before this year ends.

Mr Heard's writing is lively and offbeat. He does what he can to avoid treating his subjects as delusional crackpots and, without actually entering their belief-worlds himself, makes every effort to imagine what it is like to reside there. Yet he keeps fact and fantasy clear enough in his own head and, despite a sympathetic ear, cannot really hide the fact that this book is an extended visit to the epistemic zoo.

Eugen Weber's “Apocalypses” is altogether more interesting and informative. A noted historian of ideas, he traces millennial fears and longings in the West from their pre-Christian roots in Persian, Hebrew and Greek Stoic thought right up to Jonestown, Waco and Heaven's Gate. He points out that reckoning in centuries is a very modern phenomenon, that “millennium” in the Christian apocalypse meant simply a long time and that, since the writing of the Book of Revelation, there has hardly been a moment when somebody somewhere was not claiming that the end was nigh.

The end in question was the second coming of Christ, who would arrive either to judge and cleanse a wicked world or as the liberator of down-trodden mankind. Either way, he would come as a radical redeemer, a figure appealing equally to religious and political prophets. Yet Mr Weber disagrees with previous writers such as Norman Cohn who treated millennial prophecy as the voice of the marginal, the disoriented or the oppressed. He too sees it as a reaction, but of a different kind.

Among early Christians, the millennialists were those, frowned on by Jerome and Augustine, who wanted to keep alive the excitement of a prophetic creed in the face of an institutionalising state religion. Mr Weber detects a similar reaction in the survival of millennial beliefs into recent times, which he treats as the embers of resistance to science and enlightenment.

Along the way, Mr Weber's lively survey brings in the stars of chiliastic prediction from Montanus in the second century and Joachim of Fiore in the 12th to the pseudo-messiahs of the Reformation. He shows how easily Christian millennialism declines into anti-Semitism (before Christ's second coming, the Jews must convert). But perhaps his best chapter is on 19th-century America, where he distinguishes the reformers who prepared Christ's coming, as they saw it, by combating slavery, alcohol and other social evils, from the separatists, who withdrew into their own sects and cults, the better to wait out Christ's judgment on an unrescuable world. All in all, this is a fascinating brief history of a powerful but often hidden thread in western ways of thought.